On Wed, Feb 10, 2021 at 10:10:21AM +0800, Bin Meng wrote: > From: Bin Meng <[email protected]> > > Per MPC8548ERM [1] chapter 14.5.3.4.1: > > When RCTRL.RSF is 1, frames less than 64 bytes are accepted upon > a DA match. But currently QEMU does the opposite. This commit > reverses the RCTRL.RSF testing logic to match the manual. > > Due to the reverse of the logic, certain guests may potentially > break if they don't program eTSEC to have RCTRL.RSF bit set. > When RCTRL.RSF is 0, short frames are silently dropped, however > as of today both slirp and tap networking do not pad short frames > (e.g.: an ARP packet) to the minimum frame size of 60 bytes. So > ARP requests will be dropped, preventing the guest from becoming > visible on the network. > > The same issue was reported on e1000 and vmxenet3 before, see: > > commit 78aeb23eded2 ("e1000: Pad short frames to minimum size (60 bytes)") > commit 40a87c6c9b11 ("vmxnet3: Pad short frames to minimum size (60 bytes)") > > [1] https://www.nxp.com/docs/en/reference-manual/MPC8548ERM.pdf > > Fixes: eb1e7c3e5146 ("Add Enhanced Three-Speed Ethernet Controller (eTSEC)") > Signed-off-by: Bin Meng <[email protected]>
Applied to ppc-for-6.0.
>
> ---
>
> Changes in v3:
> - remove the slirp/tap networking workaround and only do the reverse
>
> Changes in v2:
> - rewrite the commit message and reverse the RCTRL.RSF test logic
>
> hw/net/fsl_etsec/rings.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/net/fsl_etsec/rings.c b/hw/net/fsl_etsec/rings.c
> index 121415a..fe055d3 100644
> --- a/hw/net/fsl_etsec/rings.c
> +++ b/hw/net/fsl_etsec/rings.c
> @@ -502,7 +502,7 @@ ssize_t etsec_rx_ring_write(eTSEC *etsec, const uint8_t
> *buf, size_t size)
> return -1;
> }
>
> - if ((etsec->regs[RCTRL].value & RCTRL_RSF) && (size < 60)) {
> + if (!(etsec->regs[RCTRL].value & RCTRL_RSF) && (size < 60)) {
> /* CRC is not in the packet yet, so short frame is below 60 bytes */
> RING_DEBUG("%s: Drop short frame\n", __func__);
> return -1;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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